NEW YORK (Reuters Health) - A new study shows people who are depressed may be a little more likely than others to suffer a stroke down the road.

Looking back at 28 past studies, researchers estimated there would be 106 extra cases of stroke per 100,000 depressed people each year, 22 of them fatal.

But don't reach for the antidepressants just yet, because the study has major limitations.

The biggest problem is that nobody knows how to account for the link -- people who have the blues might smoke more and exercise less, for instance. Indeed, accounting for that did weaken the apparent tie between depression and stroke, which kills about 137,000 Americans a year.

And there's a more troubling possibility, said An Pan, a researcher at Harvard School of Public Health in Boston who worked on the study.

In an earlier study, he found depressed people who take antidepressants appeared to have an increased risk of stroke compared with depressed people who weren't on the drugs.

"These medications could be one possible reason for the increased risk of stroke in depression and the majority of studies did not control for this," he told Reuters Health.

He stressed, however, that antidepressant use might also just be an indicator of severe depression, which might account for the extra risk.

"The current data on whether medications have an independent role (in stroke) is not clear at this moment," Pan said.

The findings, published in the Journal of the American Medical Association, are based on a total of more than 317,000 people followed for two to 29 years.

For health providers treating depressed people, the results add one more health problem to watch out for on a list that already includes chronic diseases like diabetes and heart disease.

But for a person with the blues, they don't mean a whole lot, said Pan.